I 've wondered more than once why TNG was the only series that didn't have a "evil mirror crew" episode of some kind. TOS, DS9, and ËNT had the mirror universe, VOY not, but had the holosimulation of "Living Witness". TNG only had Lore (ok, and Thomas Riker but he wasn't exactly evil).
I read they didn't want to make one unless they could figure out a new spin on it, and they didn't manage to do that until DS9's mirror episodes. And the world depicted in those made a "mirror Enterprise-D" difficult, since the Terran empire had fallen and all.
Also Voyage didn't have one either.